1. Field of the Invention
The invention relates to fluid collection apparatus for cylinder and ram assemblies, and more particularly, to an improved device for preventing leakage of hydraulic fluid from stuffing boxes.
2. History of the Prior Art
Heavy industrial machinery often includes components thereof which incorporate hydraulic piston and cylinder assemblies. Such assemblies utilize relative axial movement between the piston and the cylinder. In particular, high pressure hydraulic cylinder and piston arrangements are common throughout the heavy equipment industry. The use of a hydraulic cylinder and piston, by definition, requires the use of a hydraulic fluid which is a type of oil particularly suited for being placed under very high pressure and transfering forces within a piston-cylinder assembly. This pressurized oil is the medium by which the piston member is urged to reciprocate into and out of an enveloping cylinder member. Axial movement of a piston shaft into and out of one end of a cylinder requires highly reliable seals between the piston rod and the cylinder walls in order to prevent leakage of the highly pressurized hydraulic fluids out of the cylinder and into the environment. In order to minimize fluid leakage from a hydraulic cylinder, stuffing box structures have been implemented which structures include various resilient wipers that act against the surface of the moving piston shaft to form a hopefully leak proof seal.
Resilient members wear during the course of routine reciprocation of the piston into and out of the cylinder, and in practice, all stuffing boxes eventually leak with wear and age. Additionally, operational stresses as well as poor maintenance can produce misalignment between the axis of the cylinder and that of the reciprocating shaft. Shaft misalignment further aggravates wear and results in the misalignment of the seals with the shaft thereby producing leakage and/or seal rupture. Leakage is both an equipment function problem and a pollution problem
The principle reason for concern over any leakage of hydraulic fluid from stuffing box is one of safety. The slightest amount of an oily substances such as hydraulic fluid on the floor of a working area constitutes a great hazard, particularly around heavy equipment. A combination of such substances and an unobservant worker can very easily result in slippage and the possibility of a very dangerous fall. Additionally, spilled hydraulic fluid is a fire hazard and requires extra maintenance services to clean up. Hydraulic fluid is also relatively expensive and it is always economically desirable to avoid waste due to leakage of fluid into the environment.
A number of solutions have been proposed to the dilemma of the leakage of fluid from hydraulic equipment and particularly the stuffing box portion of a piston and cylinder combination. The solutions have ranged from a small cap portion covering the stuffing box face and having an end spaced from the shaft, to the addition of a second stuffing box bordering the first in order to double the protection against leakage. Each of these prior art devices has a number of disadvantages. Either, the particular design does not form a complete seal against the shaft to reliably foreclose leakage or it does not handle the difficulty inherent in leakage by the second, redundant stuffing box. Expense and difficulty of repairability are coexistant disadvantages. Such devices often require substantial maintenance and sometimes cannot be readily fitted on to an existing stuffing box due to the configuration of the particular equipment in which that stuffing box is being used. Hydraulic equipment comes in a myriad of assorted sizes, shapes and related configurations. The problem is particularly acute with today's hydraulic systems in which the ram may have a diameter of six feet or greater. Such systems have bolt circles which vary greatly in configuration. Thus, although several different systems may have identical six foot diameter rams, a single oil collection device capable of being adapted to each system has heretofore not been available.
It is desirable therefore to provide a fluid collection and anti-pollution device for stuffing boxes which overcomes the disadvantages of the prior art. The present invention, as hereinafter defined, provides such an apparatus for fluid collection by utilizing a flexible sleeve positioned about the face of a shaft-cylinder assembly. The sleeve is adapted for effectively sealing and collecting fluid which may leak and/or surge past the conventional stuffing box seals of a variety of different hydraulic system designs. Thus, spillage may be controlled with an inexpensive, versatile device adapted for being retrofitted onto many diverse configurations of stuffing boxes.